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Remember when a glass of wine at a local restaurant meant red, white, or rosé?

Many wine lists now are as fat as phone books, and glasses of wine can command as much money as entrées. But nothing expresses the ascendance of wine in Washington quite like the prevalence of wine bars.

In every corner of the region, these sip-and-graze cafes are answering the call for casual dining, combining the small-plates trend with new and interesting varietals. As tapas and mezze have erased the traditional boundaries among courses, wine drinkers are asking: Why commit to an entrée and a bottle of Merlot when you can nibble several small dishes and sample an exotic Georgian Saperavi?

At Veritas, near Dupont Circle, as many as 70 wines are offered by the glass. Cork in Logan Circle and Proof in Penn Quarter can’t match Veritas’s by-the-glass list, but their selections are wonderfully varied and full of imagination.

Wine lovers are the most obvious beneficiaries of the trend, but any diner who has ever despaired over a wine served at the wrong temperature stands to gain by the new technology. The best wine bars know how to treat wine. “The starting point is how you store and serve the wine,” says Elias Hengst, co-owner and manager of Sonoma on Capitol Hill and Redwood in Bethesda.

Hengst uses a system called Winekeeper that dispenses precise amounts of three dozen wines and keeps them at the proper temperature. The system also injects nitrogen into the bottle to keep oxygen away and maintain the wine’s freshness.

McLean’s Evo Bistro employs a similar temperature-control system but puts control over its 32 wines into the hands of the customer, not a bartender. Diners insert a debit card into a dispenser and choose among one-, three-, and five-ounce pours.

What makes a good wine bar? Some are full restaurants with strong wine programs. Others are more like traditional bars—places to have a drink on the way to or from a more substantial meal elsewhere.

Cork succeeds at being both a restaurant and a wine bar. The all-European list—a gutsy call as the dollar slides against the Euro—plumbs unfamiliar regions for little-known gems, while the array of small plates, overseen by onetime CityZen sous-chef Ron Tanaka, is interesting and lively.

Diane Gross and Khalid Pitts, the husband and wife who own and operate Cork, did their research in the wine bars of New York City, Los Angeles, Rome, and Paris before opening their own back home. “One of the nice things about creating a wine bar,” Gross says, “is that you have the freedom to create the place you want because there is no definitive model you must follow.”

That said, Cork’s competitors would do well to study its blueprint. Wine bars aren’t going away, and at the moment Cork is the best of a very large pack.

Rating System

**** (four stars) A good combination of wine, food, and atmosphere. The wine list is extensive enough to offer wines from new regions or unfamiliar grape varieties. The menu may not represent a full-scale restaurant, but quality is high and you can fashion a meal from the selections.

*** (three stars) A good experience with an interesting wine selection. Generally stronger in wine than in food.

** (two stars) A nice neighborhood destination for sipping and grazing.

* (one star) A wine bar in name only.

More than 30 wines by the glass are available at Proof.

The Trendsetters

**** Cork (1720 14th St., NW; 202-265-2675). Open since January, Cork seems to have hit upon the perfect formula of mood and food—plus more than 40 wines by the glass and many more by the bottle. The owners succeed by finding good wines from unusual regions where prices haven’t yet climbed—look for the refreshing white Larredya Jurançon, a Gros Manseng from southwestern France, or the Vajra Langhe Rosso from northern Italy. The menu of small plates meant for sharing is worth the trip even without wine—especially the wine-braised lamb with pomegranate, the crispy duck confit, and the fries dusted with parsley, lemon zest, and garlic and served with a slightly spicy house-made ketchup.

Insider tip: Four flights, listed on the chalkboard by the bar, offer chances to compare three wines of similar grapes, styles, or regions. The flights change monthly.

*** Enology (3238 Wisconsin Ave., NW; 202-362-0362). This is the Cleveland Park cousin to Dupont Circle’s Veritas but in a brighter, more inviting space and with an all-American list and menu. The top-notch list features 78 wines by the glass and boasts several wines of unusual grape varieties, such as the J. Lohr Validiguié and Jacuzzi Family Nero d’Avola from California and the Dr. Konstantin Frank Rkatsiteli from New York’s Finger Lakes. The finger food is uneven—the charcuterie is fine, but the cheeses have been unevenly ripened. And the wan flatbreads may leave you staring longingly at the throngs across the street at 2 Amys.

Insider tip: Happy hour, from 5 to 7, offers discounted wines by the glass, and daily specials include half-price bottles on Tuesdays. The waitstaff is extremely knowledgeable about the list and can be trusted to steer you toward the right wine for your cured meats.

*** Proof (775 G St., NW; 202-737-7663). This trendy Penn Quarter haunt doesn’t bill itself as a wine bar, but it’s more satisfying if you think of it as a place to sip and graze rather than to indulge in a full meal. The highlight is an extensive selection of wines, with more than 30 by the glass displayed behind the bar in a temperature-controlled system. The full list features high-ticket fantasy wines, but it takes care of thriftier drinkers, too. The kitchen tends to use salt and bacon so heavily that even powerful wines can be overwhelmed.

Insider tip: Start your visit in style by asking for the Champagne cart. Its unusual selection of bubbles on a recent visit included a sparkling Grüner Veltliner from Austria and a small-grower Champagne from Pierre Peters.

*** Redwood (7121 Bethesda La., Bethesda; 301-656-5515). A restaurant-and-wine bar combo in the new Bethesda Row from the owners of Sonoma. The setting may be bigger and glitzier, but the formula’s the same: stylized pub grub in the bar and a more formal menu in the dining room, with a modest—but growing—and well-chosen wine list that emphasizes the Pacific Coast (California, Oregon, and Washington) with occasional forays around the rim to Argentina, Chile, and New Zealand. Sommelier Brian Cook carries over the restaurant’s theme of sourcing organic ingredients and is highlighting wines grown with sustainable viticultural practices.

Insider tip: A new format for by-the-glass pours offers three sizes—100, 250, and 500 milliliters—allowing couples and small groups to explore a variety of wines together.

*** Veritas (2031 Florida Ave., NW; 202-265-6270). The selection of more than six dozen wines, primarily small-production vintages from the New World—that is, places other than Europe—is music to a wine lover’s ears. The food menu is limited to pâtés, charcuterie, cheeses, cured vegetables, dips, and desserts, so don’t come looking for a balanced meal. Its recently opened cousin in Cleveland Park, Enology, features all-American fare.

Insider tip: More-expensive selections, such as a Ridge Montebello Cabernet Sauvignon, are also offered by the half glass, so sampling a legendary wine isn’t going to rival a mortgage payment.